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HIGH TAU LOAD IS COUPLED WITH BOTH AMYLOID-BETA PATHOLOGY AND FAST FUTURE COGNITIVE DECLINE
Abstract
Aims
Amyloid-beta Positron Emission Tomography (PET) efficiently detects Alzheimer’s disease (AD) pathology in cognitive impaired patients, but lacks specificity regarding the prediction of future cognitive status. The increasing validation of tau PET tracers raises questions about whether this biomarker could predict clinically relevant cognitive decline in the AD continuum.
Methods
We selected 293 subjects [cognitive normal (CN; n=196), mild cognitive impairment (MCI; n=80), dementia (n=17)] with baseline amyloid-beta and tau PET scans that have completed a follow-up of at least two years, from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) dataset. Based on Alzheimer’s Disease Assessment Scale–Cognitive Subscale (ADAS-Cog) and linear mixed-effects models, all individuals were clustered as either fast or slow decliners. Group comparisons and accuracy of discrimination were tested.
Results
The individuals with amyloid-beta positivity and fast cognitive decline showed the highest tau PET binding values independently of baseline cognitive status, compared to the other groups (amyloid-beta negative with fast or slow decline and amyloid-beta positive with slow decline). Baseline tau PET binding could determine fast decliners with a amyloid-beta positive scan with an accuracy of 87% (composite temporal region of interest). Tau PET showed a similarly high accuracy to determine patients with MCI that would be both amyloid-beta positive and show a progress in their diagnosis at follow-up.
Conclusions
High baseline tau load is coupled with both amyloid-beta pathology and an accelerated profile of cognitive decline. Tau PET usage could offer substantial advantages over amyloid-beta PET since it gives information about the underlying pathophysiology and prognosis of the disease.